WELLFLEET — It probably goes without saying that any director is legitimately entitled to a degree of interpretive license.

But in her Wellfleet Harbor Actors Theater production of Tennessee Williams’s “Cat on a Hot Tin Roof,’’ Elizabeth Falk — who is credited with “script redaction’’ in addition to directing — has used that license in a debatable way, diminishing some of the play’s unsettling force.

Williams’s 1955 drama about greed, betrayal, mendacity (to borrow a much-used word from the play), and family infighting is a bubbling cauldron of outsize emotions.

Maggie, played by Madeleine Lambert with restless energy but an uncertain Southern accent, confronts a dilemma: Her alcoholic husband, Brick, portrayed by Steven DeMarco, will no longer sleep with her. Maggie cheated on Brick with his best friend, Skipper. Brick may or may not have been in love with Skipper, who is now dead. DeMarco is an imposing physical presence, but doesn’t project the magnetism necessary to explain the emotional hold Brick has on those around him. In fairness, the part is underwritten; there are lengthy periods where Brick is onstage but silent.

It’s not just sexual desperation and her thwarted love for Brick that make Maggie pace so restlessly around their bedroom: There’s a tactical reason for her to get pregnant. Brick’s father, Big Daddy, is dying of cancer — though he doesn’t know it — meaning that the patriarch’s sprawling plantation is up for grabs, and Brick’s scheming brother and sister-in-law are ready to pounce. They have five children and a sixth on the way, while Brick and Maggie are childless, a circumstance viewed with disfavor by Big Daddy and his wife, Big Mama.

More coverage

They are ably portrayed by real-life husband and wife Keir Dullea and Mia Dillon. Dullea is especially good as Big Daddy; he seems to have a firmer fix on his character than anyone else in the cast. The actor clearly knows this play on a bone-deep level.

Which brings me, indirectly, to my chief qualms about this production. Dullea starred as Brick in a much-lauded 1974 Broadway revival of “Cat’’ that employed a script that had been substantially revised by Williams. The playwright sought to incorporate some ideas that had been in original drafts but abandoned in the run-up to the Broadway premiere. Of particular note was a more tough-minded ending.

Rather than giving Maggie the last word — where she tells Brick of her determination to bring him back to the land of the living while touching his cheek as an apparent prelude to lovemaking — Williams’s revised version gave the final line to Brick. And it’s a meaningful one. After Maggie fervently tells her husband she loves him, Brick replies (in a chilling echo of an earlier remark made by Big Daddy in response to Big Mama): “Wouldn’t it be funny if that was true?’’

Ending the play that way, on a literal and figurative question mark, lent a tantalizing, enigmatic air of mystery to “Cat.’’ No less a playwright than Edward Albee praised “Tennessee’s reinstatement of the irony and ambiguity in the final moments of the play. . . ” But while the WHAT production largely follows Williams’s 1974 version of the script, Falk has chosen to cut Brick’s final line, and to end on a more straightforwardly upbeat note.

Yes, justification for that kind of hopeful and affirmative finale can be found in the early published version of the script, which Falk builds the WHAT ending around. But it feels here as if Falk is straining after a happy ending, especially when coupled with the way she handles the final scene between Big Daddy and Big Mama. The director has concocted a wordless Act 3 moment of loving reconciliation between the duo, even though Big Daddy has hitherto demonstrated nothing but complete scorn, even loathing, for his wife. His death’s-door conversion to decency and compassion doesn’t ring true in the least.

What does work in the WHAT production, and quite evocatively, too, is Falk’s addition of a wordless prologue, set in 1918, that features the two gay men who originally owned the Mississippi plantation. It’s tender but also unflinching in its depiction of life’s hard reality, and as such it seems to fit the spirit, if not the letter, of “Cat on a Hot Tin Roof.’’

Speaking of last words, let’s give it to Williams, who wrote of “Cat’’ and its challenges: “I don’t think a soft, or sentimental ending, can do anything but injury to the play which says only one affirmative thing about ‘Man’s Fate’: that he has it still in his power not to squeal like a pig but to keep a tight mouth about it . . . and also that love is possible: not proven or disproven, but possible.’’

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.

Thanks & Welcome to Globe.com

You now have unlimited access for the next two weeks.

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.